Sewage pump or the like



March 5, 1968 K. A. DAHLGREN ET AL 3,371,613

SEWAGE PUMP OR THE LIKE Filed April 21, 1966 I m (I l v I Q U74 I 11 l IA l i 18 3 Tix 8 5" 19 4 13' 12 14 i 6 I! United States Patent Office3,371,613 SEWAGE PUMP OR THE LIKE Jens Karl Adolf Dahlgren, Stockholm,and Carl Evert Sjiistrand, Solna, Sweden, assignors to Stenberg-FlygtAB, Solna, Sweden, a corporation of Sweden Filed Apr. 21, 1966, Ser. No.544,160 Claims priority, application Sweden, Apr. 30, 1965, 5,741/ 65 5Claims. (Cl. 103-87) ABSTRACT OF THE DISCLOSURE A water cooled sewagepump having a cooling chamber surrounding the pump motor which receivescooling water by forced circulation from the pumped sewage. The pumpimpeller is provided with vanes which draw water from the pumped sewagewhile separating the sludge therefrom and causes it to circulate throughthe cooling chamber.

The present invention relates to a pump for sewage, pulp or the like.The sewage from a large number of buildings is collected in sewagestations or catch basins. Their location may be such that the watercannot flow by gravity to the sewerage system, for instance when thecentral main of the building runs below the sewerage system level orwhen the sewage is to be carried through elevated ground sectons. Insuch cases pumps are usually used, which are specially designed forconveying sewage. These pumps have, i.a. a large-size impeller channelarea in order to allow free passage of the sizable material.

The composition of sewage can be very variable especially if anindustrial plant is connected into the sewage collecting station. Verycommonly encountered sizable materials in sewage are cotton waste,nylons, towels and the like. In unfavorable circumstances such materialsmay cause breakdowns due to the obstruction of narrow passages which mayexist in the pumps.

The size of the pump assemblies is to be reduced if lowprice andlightweight pumps are to be provided. Since the pump unit itself has tobe spacious in order to reduce the chances of obstruction, it isnecessary to reduce the size of the motor unit. In this type of pumpswhich are mostly set up in moist chambers or submersed in water, themotor is fully enclosed and receives no ventilation, and therefore thedissipated heat has to be transferred through the motor casing wall tothe surrounding air or water.

In order to reduce the size of the cooling surfaces and, consequently,that of the motor, the motor casing can be cooled with water or in anyother way. Such a cooling can be achieved by bringing water to flowalong the motor casing by means of a jacket surrounding said casing orby submersing the pump in the water so that the motor casing is at leastpartly submersed in the water.

It is also possible to have the cooling water sprinkling over the motorcasing.

When pumping sewage by means of pumps submersed in it, a fullysatisfactory cooling can be attained if a level control is provided inthe sewage pit and the pump stopping level is set at such a height thata part of the motor casing is still submersed when the pump is stopped.It is however not always possible to keep the'water level at the heightrequired for an eflicient cooling of such submersedpumps. This is forinstance the case in basins with very large surface. Nor is a sufiicientcooling provided if the pump is set up dry in a separate chamber asideof the collecting pit.

The motor casing can be cooled by water sprinkling, provided a separatewell or the like is available. According to actual regulations the motorcasing cooling device 3,371,613 Patented Mar. 5, 1968 may not beconnected to the water main unless special safety measures are takenwhich, however, do not guarantee a reliable cooling in case the watermain is shut oif or a separate cooling pump breaks down, for instance.

It is a purpose of the present invention to avoid the above drawbacks byusing the pumped medium for cooling the motor, said medium beingsupplied to a separate cooling chamber. The present invention isessentially characterized in that a sealing slit for the filtration ofthe sewage water to be used for cooling is formed between the upperperipheral edge of the pump impeller and the adjacent pump casing partabreast of the pump impeller edge. Cooling water relieved of impuritiesis thus supplied to said cooling water chamber, in the following calledend cooling chamber. When pumping sewage, narrow channels are verylikely to get stuffed with mud or blocked up by solid matters. In thepump of the invention the water is however relieved from larger sizablematerial and can therefore circulate in the cooling chamber, which makesit possible to use sewage water for cooling purposes.

According to a further embodiment of the invention the rear side of theimpeller is provided with auxiliary vanes in order to create a certainback-pressure in the cooling chamber when the pump is started up as wellas for the cooling water circulation.

A further embodiment of the invention is characterized in that the pumpmotor casing is provided with a surrounding cooling jacket and that thejacket cooling water chamber thus formed between the motor casing andthe cooling jacket is provided with a cooling water inlet connected tothe end cooling chamber between the impeller and the pump cover near thepump impeller periphery and with a cooling water outlet near the pumpimpeller nave.

The invention will be described more in detail below reference beingmade to the attached drawing which shows an embodiment of the invention.

- In the embodiment shown,'the motor casing is mounted on the pumpcasing 5. The motor casing is surrounded by a cooling jacket 2 which,for instance, can be constituted by a separate member having forinstance a slightly conical shape, said member being mounted outside themotor casing 1. Alternatively, the cooling jacket may be cast integrallywith the motor casing.

The pump casing 5 is provided with a large size flowthrough area. Thisalso applies to the impeller 6 driven by a motor shaft 19. An endcooling chamber 17 is provided above the impeller 6 between saidimpeller and the motor end shield or pump casing cover 18, said endcooling chamber 17 being intended to cool the cover or the motor endshield 18 as well as the motor bearing adjacent the impeller.

The rear side of the impeller 6 is provided with vanes 8 in order tocreate a certain back-pressure in the end cooling chamber 17. It is thusprevented that sludge may penetrate through the sealing slit 12 formedbetween the upper edge of the impeller 6 and the adjacent edge flange ofthe motor casing 5, or that sizable material or textiles may obstructsaid slit or get twisted around the impeller.

Ducts 3 provided in the lower part of the motor casing 1 are connectedto ducts 4 in the pump casing 5 in such a way that cooling water iscirculated from the upper side of the impeller 6 through the coolingducts 3 as well as the cooling ducts 7. Said circulation is produced bythe vanes 8 provided on the rear side of the impeller 6. The coolingducts 7 are connected in series and arranged so that the inlet to saidducts is located at the impeller periphery where a higher pressureprevails, while the outlet from said ducts is located near the im pellernave 9 where a lower pressure prevails. A number of partition walls 10are provided inside the jacket chamber, which walls, as alreadymentioned, form ducts 7, running vertically in the embodiment shown,which ducts are communicating with adjacent ducts through ports 11.

As mentioned above, a sealing slit 12 is being provided between theimpeller 6 and the pump casing 5 in order to prevent impurities frompenetrating into the cooling chambers. Said slit is arranged in such away that sides 13 of the impeller channel protrude beyond the inner wall14 of the pump casing 5 in that a ring-shaped flange projects from saidwall 14, the solid particles being flung past the slit opening to becarried out of the pump casing 5 by the water. The cooling jacket 2 isat its top and its bottom provided with threaded and plugged lugs (15,16 respectively), which can be used for flushing the cooling system whenoverhauling the pump, for instance.

Owing to the division of the jacket cooling chamber in a number ofcooling channels arranged along a meandershaped path, water flowsthrough said channels at a high velocity so that obstruction of thechannels through mud deposits is avoided.

The flow velocity of the cooling water can be further increased byarranging the cooling water inlet in a direction corresponding to ahelical line around the cooling jacket.

Eventually the impeller may also be provided with vanes between theunderside of the impeller and the bottom of the pump casing, andcommunication ducts may be provided between the cooling water chamberthus formed and the inlet and outlet ducts of the jacket cooling chamberas indicated by dashed lines on the drawing.

The device of the invention operates as follows:

When the pump is started the water above the impeller 6 is imparted arotating movement by vanes 8 on the impeller rear side and the water ispumped into the cooling ducts 4, 3 and 7, further through the ports 11to the next cooling duct to be discharged through the outlet 17 near theimpeller nave 9. The cooling water further flows past the cooled rearside of the impeller 6 and is again pumped into the cooling channels 4,3 and 7. In addition, an exchange of cooling water occurs at the slit 12which operates as a filter. As already mentioned, the provision of anumber of ducts with a comparatively small area brings about a highwater flow velocity preventing the small particles from settling in thechannels and carrying away the air which initially is enclosed at theupper part of the cooling channels. Practical tests have shown thatenclosed air, if any, is discharged from the pump casing through theslit 12 and that the whole cooling chamber gets rapidly filled withwater.

If, when pumping pulp or the like, a sufficient separation of theparticles cannot be attained, the jacket cooling chamber can instead beused for additional separate cooling, the cover 18 being replaced by acover without duct openings or the cover being displaced so that theduct openings are obturated by an overlying or subjacent member, or theduct openings being obturated by means of plugs of a resilient materialso that the additional separate cooling can be achieved by connectingpipes for a cooling medium to the lugs and 16. This embodiment can alsobe used for pumping hot liquids.

The additional cooling can also be used if a dilution of the pumpedmedium is permissible, in which case the coolant is supplied through thelug 15 or 16, and flows through the slit sealing into the medium beingpumped. This embodiment is also suitable when it is desirable that thediluent be well mixed into the medium being pumped.

With the embodiment described above the pumping can be carried outcontinuously without overheating the motor, whether the pump issubmersed in water or not.

Although the invention has been described in connection with anembodiment shown on the drawing, it is obvious that may alterations ormodifications may be made within the scope of the appending claims.

What we claim is:

1. A sewage pump comprising an impeller, a motor driving said impeller,a pump housing surrounding said impeller, and a pump motor casing oversaid motor, said casing having a cover at one end thereof adjacent saidpump housing defining an end cooling chamber, a cooling jacketsurrounding said motor casing forming an annular cooling chambertherebetween, a sealing slit between the upper peripheral edge of saidimpeller and the adjacent pump housing portion abreast of said impellerperiphery, and auxiliary vanes on the upper side of said impeller,whereby said auxiliary vanes cause cooling water free of impurities tocirculate through said sealing slit, said end cooler cooling chamber andsaid cooling jacket, said cooling water entering said cooling jacketthrough an inlet connected to the end cooling chamber between saidimpeller and said pump housing near said impeller periphery and saidcooling jacket having a cooling water outlet near the nave of saidimpeller.

2. A sewage pump as in claim 1 wherein said pump is further providedwith an additional sealing slit between the lower peripheral edge ofsaid impeller and the adjacent pump housing portion abreast of saidimpeller periphery.

3. A sewage pump as in claim 1, wherein the end cooling chamber isdivided by a wall essentialy parallel to the casing cover and providedwith .a ring-shaped opening around the pump driving shaft whereby saidcooling chamber is divided into a first end cooling chamber partadjacent to said impeller where a higher pressure prevails and a secondend cooling chamber part adjacent to the casing cover where a lowerpressure prevails.

4. A sewage pump as claimed in claim 3, wherein the water inlet to thejacket cooling chamber is connected to the first end cooling chamberpart and said water outlet is connected to the second end coolingchamber part.

5. A sewage pump as in claim 3, wherein the outlet from the jacketcooling chamber is located at the second part of said jacket coolingchamber.

References Cited UNITED STATES PATENTS 2,862,120 11/1958 Onsrud 310,54.

FOREIGN PATENTS 496,115 11/1938 Great Britain. 394,811 6/1965SWiterland.

ROBERT M. WALKER, Primary Examiner.

